Biomedical subjects

B F Overholt

Publications and source records attributed to B F Overholt.

At least 19 recordsLinked to original sources

PubMed2004

What is the best management strategy for high grade dysplasia in Barrett's oesophagus? A cost effectiveness analysis.

BACKGROUND: Multiple treatment strategies for subjects with high grade dysplasia (HGD) in Barrett's oesophagus (BO) have been suggested. However, it is unclear which of these strategies provides the greatest life expectancy, and the costs associated with the management strategies are unknown. AIM: To compare the efficacy and cost effectiveness of competing management strategies for BO with HGD. METHODS: We created a decision analysis model in Data 4.0 to assess possible treatment strategies for BO with HGD. The strategies included: (1) no preventative strategy, (2) elective surgical oesophagectomy, (3) endoscopic ablation, and (4) surveillance endoscopy. The base case was a healthy 50 year old White male with an initial diagnosis of BO with HGD. The model allowed for complications of surgery, including death. Ablative therapy could cause stricture or perforation. Pathological misinterpretation was allowed, and modelled after reported rates. Estimates were derived from the literature for the rate of progression of HGD to cancer and for complication rates for the various treatment modalities. The endoscopic ablation arm was modelled as photodynamic therapy. Sensitivity analyses were performed over a wide range of cancer incidences, complication rates, and procedure costs. RESULTS: Endoscopic ablation was the most effective strategy, yielding 15.5 discounted quality adjusted life years (dQALY), compared with 15.0 for endoscopic surveillance and 14.9 for oesophagectomy. No preventative strategy was the most inexpensive option, yielding an average cost per quality adjusted life year of US dollars 54 (44) per dQALY, but resulted in high rates of cancer. Endoscopic surveillance dominated oesophagectomy, being both less costly and more effective. The condition of extended dominance occurred when comparing endoscopic ablation to endoscopic surveillance because, although the total costs of ablation were greater than those of surveillance, it was less expensive to buy an additional life year using endoscopic ablation than endoscopic surveillance. The incremental cost effectiveness ratio when moving from no therapy to ablative therapy was a reasonable US dollars 25 621/dQALY (21 009/dQALY). Sensitivity analysis demonstrated that when yearly rates of progression to cancer from HGD exceeded 30%, oesophagectomy became the most cost effective option. CONCLUSIONS: A strategy of endoscopic ablation provided the longest quality adjusted life expectancy for BO with HGD. Although endoscopic surveillance was less expensive than endoscopic ablation, it was associated with shorter survival. Optimal utilisation of healthcare resources may be achieved with endoscopic ablative therapy for BO with HGD.

Barrett Esophagus↗

PubMed2003

Development of a fluorescence detection system using optical parametric oscillator (OPO) laser excitation for in vivo diagnosis.

In this work, the development and applications of a fluorescence detection system using optical parametric oscillator (OPO) laser excitation for in vivo disease diagnosis including oral carcinoma are described. The optical diagnosis system was based on an OPO laser for multi-wavelength excitation and time-resolved detection. The pulsed Nd-YAG-pumped OPO laser system (6 ns, 20 Hz) is compact and has a rapid, broad, and uniform tuning range. Time-gated detection of intensified charge-coupled device (ICCD) making use of external triggering was used to effectively eliminate the laser scattering and contribute to the highly sensitive in vivo measurements. Artificial tissue-simulating phantoms consisting of polystyrene microspheres and tissue fluorophores were tested to optimize the gating parameters. 51-ns gate width and 39-ns gate delays were determined to be the optimal parameters for sensitive detection. In vivo measurements with the optical diagnosis system were applied to esophagus, stomach, and small intestine using an endoscope in canine animal studies. The rapid tuning capability of the optical diagnosis system contributed greatly to the optimization of wavelength for the observation of porphyrin in the small intestine. When the small intestine was thoroughly washed with water, the emission band which corresponds to porphyrin disappeared. Based on this observation, it was concluded that the detected signal was yielded by porphyrin-containing bile secretion. Also, multispectral analyses using multiple excitations from 415 to 480 nm at 5 nm intervals confirmed the porphyrin detection in the small intestine. The optical diagnosis system was also applied to the detection of human xenograft of oral carcinoma in mice using 5-aminolevulinic acid (5-ALA) which is a photodynamic therapy (PDT) drug. Significant differences in protoporphyrin IX fluorescence intensity between normal and tumor tissue could be obtained 2 hours after the injection of 5-ALA into mice due to the preferential accumulation of 5-ALA in tumors. Results reported herein demonstrate potential capabilities of the LIF-OPO system for in vivo disease diagnosis.

Animals↗

PubMed2000

Results of photodynamic therapy for ablation of dysplasia and early cancer in Barrett's esophagus and effect of oral steroids on stricture formation.

OBJECTIVE: The primary goal of this study was to investigate whether oral steroids would reduce the incidence of stricture formation after photodynamic therapy (PDT) in Barrett's patients. The effect of balloon window length, pretreatment of nodules, retreatment of skipped areas, and subsequent PDT on the incidence of strictures was also investigated. The ultimate goal of treatment was elimination of dysplasia, early cancer, and Barrett's mucosa. METHODS: A total of 60 patients were injected with Photofrin (2 mg/kg). Patients were randomized to receive PDT (n = 30) or PDT and oral prednisone (n = 30). Two days later, 630 nm light (KTP/dye laser) was delivered using a 5- or 7-cm windowed balloon at a light dose of 200 or 175 J/cm. The majority of patients received 200 J/cm using a 7-cm balloon. Nodules were pretreated with a short diffuser at a dose of 50-75 J/cm. Additional light was delivered to skipped areas 2-3 days later. Endoscopies were conducted every 3-6 months to evaluate the response. Residual or recurrent Barrett's was treated using neodymium:aluminum-yttrium-garnet (Nd:YAG) laser (small areas) or was retreated with PDT. RESULTS: The effect of steroids on the incidence of strictures was analyzed in patients receiving a single treatment with a light dose of 200 J/cm using a 7- cm balloon. There was no reduction in the incidence of strictures in patients receiving PDT and steroids (29%) compared to those receiving PDT alone (16%). Treatment using a 7-cm balloon caused more strictures (31%) than treatments using a 5-cm balloon (7%). Pretreatment of nodules or retreatment of skipped areas did not increase strictures. Patients receiving subsequent PDT had a higher incidence of strictures. Cancer was eliminated in all patients. High-grade dysplasia was eliminated in 41 of 43 patients (96%). Barrett's mucosa was totally eliminated in 25 of 60 patients (42%). CONCLUSIONS: Oral prednisone after PDT did not reduce the incidence of strictures. Subsequent PDT and longer balloon window were associated with higher incidence of strictures. PDT followed by thermal ablation of small islands eliminated dysplasia, early cancer, and Barrett's mucosa.

Administration, Oral↗

PubMed2000

Light sources and delivery devices for photodynamic therapy in the gastrointestinal tract.

This article provides discussion on different light sources and light delivery devices used for photodynamic therapy of a variety of gastrointestinal malignancies. Different laser and nonlaser sources are discussed with emphasis on most commonly used clinical units. The discussion of light delivery devices is divided into several sections, each reviewing the evolution of fiberoptic delivery devices for different gastrointestinal malignancy. A discussion is provided on power meters and wavelength calibration devices used to assure proper light dosimetry. Finally, a short discussion is provided on a technique used to improve endoscopic monitoring of photodynamic therapy procedure during the treatment.

Endoscopy, Gastrointestinal↗

PubMed2000

Evaluating treatments of Barrett's esophagus that shows high-grade dysplasia.

Thermal ablation and surgery are currently indicated for the treatment of Barrett's esophagus that shows high-grade dysplasia. Recent clinical thought is that photodynamic therapy (PDT), a nonsurgical ablative therapy, along with proton pump inhibitor therapy, may be able to eliminate Barrett's esophagus with less morbidity and mortality, and perhaps at a lower cost, than other current treatments. PDT is currently under investigation for this indication. The principles of ablative therapy, complications of PDT, treatment results, the best candidates for PDT, and the workup strategy are discussed.

Barrett Esophagus↗

PubMed1999

Photodynamic therapy for Barrett's esophagus: follow-up in 100 patients.

BACKGROUND: This report presents clinical results of photodynamic therapy in patients with Barrett's esophagus and dysplasia or superficial esophageal cancer. METHODS: One hundred patients including 13 with superficial cancers were treated. Light (630 nm) was endoscopically delivered to the esophageal mucosa by a diffuser or a windowed esophageal centering balloon. Nd:YAG laser was required to ablate small residual areas of Barrett's mucosa during-long-term follow-up. Patients were maintained on omeprazole and were followed for 4 to 84 months (mean 19 months). RESULTS: Conversion of approximately 75% to 80% of treated Barrett's mucosa to normal squamous epithelium was found in all patients; complete elimination of Barrett's mucosa was noted in 43 patients. Dysplasia was eliminated in 78 patients. Dysplasia developed during follow-up in 11 of 48 patients in untreated Barrett's mucosa requiring additional therapy. Ten of the 13 malignancies were ablated. Esophageal strictures occurred in 34%. Use of longer centering balloons reduced the incidence of strictures. CONCLUSION: Photodynamic therapy alone or with Nd:YAG laser thermal ablation combined with long-term acid inhibition provides an effective endoscopic therapy to (1) eliminate Barrett's mucosal dysplasia and superficial esophageal cancer and (2) reduce the extent of and, in some cases, eliminate Barrett's mucosa.

Adenocarcinoma↗

PubMed1999

Characteristics of best gastroenterology practices.

OBJECTIVE: As health care costs continue to rise, competition among providers is increasing. Although this competition is currently based on price, quality of care will become an increasingly important issue. One popular method to assess quality is by comparing physicians' performance with that of a representative group of physicians, in a process called benchmarking. The purpose of this study was to survey private practice gastroenterologists to identify the practice characteristics, so-called "best practices," associated with high-quality health care delivery to provide data for use as benchmarks. METHODS: Three hundred randomly selected gastroenterology practices were surveyed regarding practice demographics, administration, financial management, and use of outcomes techniques by mail questionnaire. Analogous questionnaires were completed by representatives of the gastroenterology practices comprising the Gastroenterology Practice Management Group, LLC (GMPG). RESULTS: One hundred and eighty-two (61%) of the 300 eligible practices responded to the questionnaire. Increasing differences between survey and benchmark GPMG practices were observed as the complexity of quality measures increased. Among structure measures, the groups were similar. By contrast, significant differences were observed between survey and benchmark groups with regards to outcomes measures such as the use of practice guidelines, continuous quality improvement, and outcomes assessment. CONCLUSIONS: These results provide a snapshot of gastroenterology practices across the country and can be used as a benchmark for quality assessment purposes to compare with one's practice, suggesting areas for change or improvement. It seems clear that the defining characteristic of best gastroenterology practices is the demonstration of quality patient care. It also appears that many practices' efforts in this regard could be increased.

Gastroenterology↗

PubMed1999

Results of photodynamic therapy in Barrett's esophagus: A review.

Barrett's esophagus is associated with an increased occurrence of mucosal dysplasia and adenocarcinoma in the specialized glandular mucosa, with a 30- to 52-fold increase in the occurrence of esophageal cancer compared with the normal population. An alternative to esophagectomy as a treatment modality is needed because of the high morbidity and mortality associated with it. Photodynamic therapy offers an alternative nonsurgical therapy that eliminates dysplasia and superficial cancer, and reduces Barrett's mucosa while reducing the risks and costs compared with those of esophagectomy. The use of photodynamic therapy in the ablation of Barrett's mucosa is reviewed.

Barrett Esophagus↗

PubMed1998

Laser-induced fluorescence for esophageal cancer and dysplasia diagnosis.

A method using laser-induced fluorescence (LIF) for in vivo cancer diagnosis of the esophagus is described. Autofluorescence of normal and malignant tissues was measured directly using a fiberoptic probe inserted through an endoscope. The measurements were performed in vivo during routine endoscopy. Measurement of the fluorescence signal from the tissue was performed using laser excitation at 410 nm. The methodology was applied to differentiate normal and malignant tumors of the esophagus. The results of this LIF approach were compared with histopathology results of the biopsy samples and indicated excellent agreement in the classification of normal and malignant tumors for the samples investigated. The LIF procedure could lead to the development of a rapid and cost-effective technique for cancer diagnosis.

Barrett Esophagus↗

PubMed1997

Photodynamic therapy for Barrett's esophagus: cardiac effects.

BACKGROUND AND OBJECTIVE: Atrial fibrillation has been reported following esophageal photodynamic therapy. This study presents the results of serial cardiac testing following photodynamic therapy for patients with Barrett's esophagus and with dysplasia or early carcinoma. STUDY DESIGN/MATERIALS AND METHODS: Twelve patients were treated using photodynamic therapy. Serum creatinine phosphokinase and lactic dehydrogenase isoenzyme levels were determined pretreatment and 24, 48, and 72 hours after treatment. Electrocardiograms were obtained before and 48 hours after treatment. A rhythm strip was obtained 1 week posttreatment. Clinical assessment for cardiac arrhythmias occurred daily following therapy. RESULTS: Transient atrial fibrillation was noted in one patient during a follow-up endoscopy. However, no significant or permanent abnormality was noted in cardiac enzymes or electrocardiograms. CONCLUSION: No permanent electrocardiographic changes or significant abnormalities in cardiac enzymes were detected following esophageal photodynamic therapy in patients with or without histories of cardiac disease. Delivery of esophageal PDT is not associated with permanent adverse cardiac effects.

Adult↗

PubMed1997

Physician profiling and capitated income distribution.

Increasingly, gastroenterologists are addressing the practice issues of physician profiling and capitation. This article describes a method to easily create practice-generated physician profiles that are used in quality of care management and contracting decisions. These profiles are also used as part of a method for capitation revenue distribution that is described and that has been used by the author's practice for over 3 years. This capitation revenue distribution methodology properly rewards the provision of cost-effective care and bonuses desirable to physician-patient relationships, while protecting against under- or over-utilization.

Capitation Fee↗

PubMed1997

Photodynamic therapy for Barrett's esophagus.

In summary, in a group of 55 patients with Barrett's esophagus and dysplasia, the authors have reported the ablation of seven superficial cancers, the elimination of dysplasia in 42 of the 55 patients, the complete elimination of Barrett's mucosa in 16 patients, and the reduction of the extent of Barrett's mucosa in all patients who were treated with PDT and were maintained on long-term omeprazole. Repeated PDT sessions were required in some patients to accomplish elimination of dysplasia. Esophageal strictures occurred in 53% of patients, but were treated satisfactorily with dilation. Current results using 5- and 7-cm centering balloons has shown a dramatic reduction in the incidence of stricture formation. Mucosal injury with these balloons is less than with diffusers or shorter balloons that require overlapping of treated areas. The authors are carefully following the patients treated with longer PDT balloons to evaluate the long-term effects on dysplasia. Lugol's staining is an important technique to identify residual patches of Barrett's mucosa following PDT. Small residual patches of Barrett's mucosa can be successfully destroyed with Nd: YAG laser therapy. The authors' results indicate that PDT alone or in combination with thermal ablation can eliminate superficial cancers, dysplasia, and Barrett's mucosa in many patients with Barrett's esophagus.

Barrett Esophagus↗

PubMed1996

Balloon photodynamic therapy of esophageal cancer: effect of increasing balloon size.

BACKGROUND AND OBJECTIVE: Photodynamic therapy is currently being used to treat various malignancies including esophageal cancer. The effect of photodynamic therapy depends upon the concentration of photosensitizing drug, light energy delivered to tissue, and the presence of oxygen in the targeted tissue. We have found that an esophageal centering balloon improves light delivery to esophageal mucosa. However, balloon pressure on esophageal mucosa could possibly reduce mucosal blood flow and oxygenation, therefore reducing the effect of photodynamic therapy. This study was conducted to investigate the effect of balloon pressure on the esophageal wall during photodynamic therapy in the canine esophageal model. STUDY DESIGN/MATERIALS AND METHODS: Studies were performed in the canine esophagus of ten animals to investigate whether increasing the size of the centering balloon, and hence the pressure on esophageal mucosa, would alter the tissue effect of PDT. Porfimer sodium 4 mg/Kg was administered and 630 nm light was delivered via a 1 cm diffuser located in the center of a 360 degrees 2 cm windowed balloon. Mucosal light measurements were made to ascertain equivalent mucosal light dosing of approximately 25 J/cm2. Endoscopic and necropsy findings obtained following photodynamic therapy with 25 mm, 33 mm, and 35 mm balloons were compared. RESULTS: In larger dogs (groups A and B), increasing the size of the esophageal centering balloon from a 25-33 mm size did not result in an overly tight fit nor was the increase associated with significant change in the PDT effect. In contrast, increasing the balloon size to 35 mm in smaller dogs (group C) resulted in a tight fit of the balloon in the esophagus and in significant reduction in the PDT effect on mucosal damage when mucosal equivalent light dose was administered during photodynamic therapy in the canine esophageal model. CONCLUSION: Increasing centering balloon size resulted in reduced tissue damage when mucosal equivalent light dose was administered during photodynamic therapy in the canine esophageal model. Proper sizing of centering balloons will be necessary for balloon PDT of esophageal mucosal dysplasia or cancer in humans.

Animals↗

PubMed1996

Endoscopic fluorescence detection of high-grade dysplasia in Barrett's esophagus.

BACKGROUND & AIMS: Early detection and treatment of esophageal cancer in Barrett's esophagus may improve patient survival if dysplasia is effectively detected at endoscopy. Typically, four-quadrant pinch biopsy specimens are taken at 2-cm intervals. This study was conducted to determine whether laser-induced fluorescence spectroscopy could be used to detect high-grade dysplasia in patients with Barrett's esophagus. METHODS: Four hundred ten-naonometer laser light was used to induce autofluorescence of Barrett's mucosa in 36 patients. The spectra were analyzed using the differential normalized fluorescence (DNF) index technique to differentiate high-grade dysplasia from either low-grade or nondysplastic mucosa. Each spectrum was classified as either premalignant or benign using two different DNF indices. RESULTS: Analysis of the fluorescence spectra from all patients collectively using the DNF intensity at 480 nm (DNF480) index showed that 96% of nondysplastic Barrett's esophagus samples were classified as benign, all low-grade dysplasia samples as benign, 90% of high-grade dysplasia samples as premalignant, and 28% of low-grade with focal high-grade dysplasia samples as premalignant. Using the two DNF indices concurrently, all patients with any high-grade dysplasia were classified correctly. CONCLUSIONS: Laser-induced fluorescence spectroscopy has great potential to detect high-grade dysplasia in Barrett's esophagus when using the DNF technique.

Adult↗

PubMed1996

Photodynamic therapy in Barrett's esophagus.

OBJECTIVES: This report presents clinical results using photodynamic therapy for dysplasia and superficial esophageal cancer in Barrett's esophagus. METHODS: Forty-five (45) patients with Barrett's esophagus and dysplasia were treated with photodynamic therapy using sodium porfimer 2.0 mg/kg as the photosensitizing drug. Fifteen patients also had 16 superficial esophageal cancers (0-1.5 cm; Tis-T2, N-0, M-0). Red light (630 nm) was delivered to the esophageal mucosa by a diffuser inserted through the endoscope or via a windowed esophageal centering balloon designed to improve targeted delivery of light during photodynamic therapy. Patients were maintained on omeprazole and were followed for 6-62 months following photodynamic therapy. RESULTS: Photodynamic therapy produced mucosal damage in treated areas. Ablation of dysplastic or malignant mucosa was followed by healing and conversion of approximately 75-80% of treated Barrett's mucosa to normal squamous epithelium in all patients. Complete elimination of Barrett's epithelium was found in 16 patients. Areas of dysplasia were eliminated in 35 of the 45 patients. All 16 malignancies were ablated. No cancer recurrence was found in follow-up. Healing was associated with esophageal strictures in 58%, which were treated successfully by esophageal dilation in all patients. CONCLUSION: Photodynamic therapy combined with long-term acid inhibition provides an effective endoscopic therapy to (1) eliminate Barrett's mucosal dysplasia and superficial esophageal cancer and (2) reduce the amount of and, in some cases, eliminate Barrett's mucosa.

Adenocarcinoma↗

PubMed1996

Photodynamic therapy for Barrett's esophagus: clinical update.

OBJECTIVES: This report presents clinical results of photodynamic therapy for dysplasia and superficial esophageal cancer in Barrett's esophagus. METHODS: Thirty-six patients with Barrett's esophagus and dysplasia were treated with photodynamic therapy, and sodium porfimer 2.0 mg/kg was used as the photosensitizing drug. Fourteen patients also had 15 superficial esophageal cancers (0-1.5 cm; ultrasound-T2,N-0,M-0). Red light (630 nm) was delivered to the esophageal mucosa by a diffuser inserted through the endoscope or via a windowed esophageal centering balloon designed to improve targeted delivery of light during photodynamic therapy. Patients were maintained on omeprazole and were followed for 6-62 months after photodynamic therapy. RESULTS: Photodynamic therapy produced extensive mucosal damage in treated areas. Ablation of dysplastic or malignant mucosa was followed by healing and conversion of approximately 75-80% of treated Barrett's mucosa to normal squamous epithelium in all patients. Complete elimination of Barrett's epithelium was achieved in 10 patients. Areas of dysplasia were eliminated in 29 patients, and all 15 malignancies were ablated. No cancer recurrence was found in follow-up. Healing was associated with esophageal strictures (four were severe) that were treated successfully by esophageal dilation in 21 patients. CONCLUSION: Photodynamic therapy combined with long-term acid inhibition provides effective endoscopic therapy that 1) eliminates Barrett's mucosal dysplasia and superficial esophageal cancer, and 2) reduces the amount of, or, in some cases, eliminates Barrett's mucosa.

Adenocarcinoma↗

PubMed1995

In vivo cancer diagnosis of the esophagus using differential normalized fluorescence (DNF) indices.

BACKGROUND AND OBJECTIVE: We report the use of new diagnostic parameters based on the differential normalized fluorescence (DNF) signals for malignant tumor diagnosis. STUDY DESIGN/MATERIALS AND METHODS: Over 200 measurements of endogenous fluorescence from normal and malignant esophageal tissues were performed during routine endoscopy in 48 patients. A pulsed nitrogen-pumped dye laser was used to provide in situ excitation at 410 nm. Direct collection of the fluorescence signal emitted by the tissue was achieved using an intensified photodiode array detector equipped with a fiberoptic probe. RESULTS: The fluorescence signals were normalized with respect to the total fluorescence signal area. The cancer diagnosis indices were defined by the difference between the normalized fluorescence signal of a tumor and the mean value of a reference set of normal tissues. The results of the DNF approach were compared with endoscopic examinations and histopathology interpretations of the biopsy samples. Excellent correlation in the classification of normal and malignant tumors for the samples was found. CONCLUSION: The data indicated that the DNF approach has a significant potential to provide a direct, real-time, and in-situ technique for cancer diagnosis of the esophagus without requiring biopsy of the tumors and time-consuming histopathology tests.

Adenocarcinoma↗

PubMed1995

Photodynamic therapy with porfimer sodium versus thermal ablation therapy with Nd:YAG laser for palliation of esophageal cancer: a multicenter randomized trial.

BACKGROUND: Photodynamic therapy (PDT) is a different type of laser treatment from Nd:YAG thermal ablation for palliation of dysphagia from esophageal cancer. METHODS: In this prospective, multicenter study, patients with advanced esophageal cancer were randomized to receive PDT with porfimer sodium and argon-pumped dye laser or Nd:YAG laser therapy. RESULTS: Two hundred thirty-six patients were randomized and 218 treated (PDT 110, Nd:YAG 108) at 24 centers. Improvement in dysphagia was equivalent between the two treatment groups. Objective tumor response was also equivalent at week 1, but at month 1 was 32% after PDT and 20% after Nd:YAG (p < 0.05). Nine complete tumor responses occurred after PDT and two after Nd:YAG. Trends for improved responses for PDT were seen in tumors located in the upper and lower third of the esophagus, in long tumors, and in patients who had prior therapy. More mild to moderate complications followed PDT, including sunburn in 19% of patients. Perforations from laser treatments or associated dilations occurred after PDT in 1%, Nd:YAG 7% (p < 0.05). Termination of laser sessions due to adverse events occurred in 3% with PDT and in 19% with Nd:YAG (p < 0.05). CONCLUSIONS: Photodynamic therapy with porfimer sodium has overall equal efficacy to Nd:YAG laser thermal ablation for palliation of dysphagia in esophageal cancer, and equal or better objective tumor response rate. Temporary photosensitivity is a limitation, but PDT is carried out with greater ease and is associated with fewer acute perforations than Nd:YAG laser therapy.

Adenocarcinoma↗